Weve landed on the moon, and launched probes to study planets hundreds of millions of miles away. But when it comes to space travel, were just babes in the woods. Of the hundreds of launches weve made into space, only a handful have even left Earths gravity. So whats the problem? Well, for one, its a huge challenge just getting off the planet. If you want to get into space you have to fly fast and high. Find out just how tough and complicated future space travel can be on Known Unive.